Integral gutter and front center body

ABSTRACT

A fan drive gear system for a turbofan engine is disclosed and includes a gear assembly and a front center body. The front center body is an annular case that supports the gear assembly. The front center body includes a passage portion that defines a portion of a core flow path, a forward flange configured for attachment to a first case structure forward of the front center body, and gutter portion disposed on a radially inner side of the front center body for collecting lubricant exhausted from the geared assembly.

REFERENCE TO RELATED APPLICATION

This application claims priority to U.S. Provisional Application No.61/868,135 filed on Aug. 21, 2013.

BACKGROUND

A gas turbine engine typically includes a fan section, a compressorsection, a combustor section and a turbine section. Air entering thecompressor section is compressed and delivered into the combustionsection where it is mixed with fuel and ignited to generate a high-speedexhaust gas flow. The high-speed exhaust gas flow expands through theturbine section to drive the compressor and the fan section. Thecompressor section typically includes low and high pressure compressors,and the turbine section includes low and high pressure turbines.

A speed reduction device such as an epicyclical gear assembly may beutilized to drive the fan section such that the fan section may rotateat a speed different than the turbine section so as to increase theoverall propulsive efficiency of the engine. In such enginearchitectures, a shaft driven by one of the turbine sections provides aninput to the epicyclical gear assembly that drives the fan section at areduced speed such that both the turbine section and the fan section canrotate at closer to optimal speeds.

Bearings supporting rotation of gears within the gear assembly requireconstant lubrication. The engines lubrication system provides lubricantduring operation but may not provide a desired lubricant flow duringsome operating conditions. During operating conditions includingmomentary periods of zero or negative gravity, lubricant flow may beless than desired. An auxiliary lubricant system supplies lubricantduring these momentary periods. The auxiliary lubricant system includesan auxiliary lubricant supply supplied from lubricant exhausted from thegear assembly. The exhausted lubricant is captured in a gutterarrangement surrounding the gear assembly and directed into theauxiliary supply. The gutter is an additional part that requiresadditional fabrication and assembly time and expense.

Turbine engine manufacturers continue to seek further improvements toengine assembly and performance including improvements that reduceexpense, ease assembly and simplify maintenance.

SUMMARY

A turbofan engine according to an exemplary embodiment of thisdisclosure includes, among other possible things includes a turbinesection, a geared architecture driven by the turbine section and a fanis driven by the turbine section through the geared architecture. Afront-center unitary body supports the geared architecture and includesa gutter for gathering lubricant exhausted from the geared architecture.An auxiliary lubricant supply is in fluid communication with the gutterfor receiving gathered lubricant.

In a further embodiment of the above turbofan engine, the auxiliarylubricant supply is defined within a first case structure and attachedto the front center body.

In a further embodiment of the above turbofan engine, the gutterincludes an outlet for communicating lubricant to the auxiliarylubricant supply. The outlet includes an extension configured toprotrude into the auxiliary lubricant supply.

In a further embodiment of the above turbofan engine, the gutterincludes an inlet for communicating lubricant from the auxiliarylubricant supply to an outlet passage defined within the gutter. Theinlet includes an outlet extension that protrudes into the outletpassage of the gutter.

In a further embodiment of the above turbofan engine, the gutter abutsthe first case structure without fasteners and communicates lubricantbetween the auxiliary lubricant supply and the gutter without seals.

In a further embodiment of the above turbofan engine, a compressorsection and a combustor section are in fluid communication with thecompressor section.

In a further embodiment of the above turbofan engine, the front centerbody defines a portion of a core flow path to the compressor section.

In a further embodiment of the above turbofan engine, the front centerbody includes an integrally formed web that extends inward to supportthe gutter proximate the geared architecture.

In a further embodiment of the above turbofan engine, the front centerbody and gutter form a single unitary case structure.

A front center body according to another exemplary embodiment includes apassage portion for defining a portion of a core flow path, a forwardflange configured for attachment to a first case forward of the frontcenter body and a gutter portion disposed on a radially inner side ofthe front center body. The passage portion and the gutter portion arecontinuous uninterrupted surfaces of the front center body.

In a further embodiment of the above, the gutter portion includes afirst channel for gathering lubricant exhausted from a gear assembly anda second channel for exhausting lubricant from an auxiliary lubricantsupply.

In a further embodiment of the above, the first channel includes anoutlet extension that protrudes axially outward for extending into anopening in the first case for communicating lubricant to the auxiliarylubricant supply.

In a further embodiment of the above, the gutter is configured tosurround a gear assembly supported within the front center body.

In a further embodiment of the above, a web portion extends between thepassage portion and the gutter portion that is an integral structure ofthe front center body case.

A fan drive gear system for a turbofan engine according to an exemplaryembodiment includes a gear assembly, a front center body supporting thegear assembly and a passage portion for defining a portion of a coreflow path. A forward flange is configured for attachment to a first casestructure forward of the front center body. A gutter portion is disposedon a radially inner side of the front center body. The passage portionand the gutter portion are continuous uninterrupted surfaces of thefront center body.

In a further embodiment of the above, the first case structure includesan auxiliary lubricant supply and the gutter portion includes an outletthat extends axially forward into the first case structure forcommunicating captured lubricant from the gear assembly to the auxiliarylubricant supply.

In a further embodiment of the above, the gutter portion includes afirst channel for gathering lubricant exhausted from the gear assemblyand a second channel for exhausting lubricant from the auxiliarylubricant supply.

In a further embodiment of the above, the passage portion, the forwardflange and the gutter portion comprise a continuous uninterruptedcross-section of the front center body.

Although the different examples have the specific components shown inthe illustrations, embodiments of this disclosure are not limited tothose particular combinations. It is possible to use some of thecomponents or features from one of the examples in combination withfeatures or components from another one of the examples.

These and other features disclosed herein can be best understood fromthe following specification and drawings, the following of which is abrief description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of an example gas turbine engine.

FIG. 2 is a cross-section of an example fan drive gear system.

FIG. 3 is a cross-section of a portion of an example gutter portion of afront center body.

FIG. 4 is a perspective view of an outlet of an example gutter portion.

FIG. 5 is a perspective view of an outlet of an example first casestructure.

FIG. 6 is a cross-section of the example front center body with anintegral gutter portion.

DETAILED DESCRIPTION

FIG. 1 schematically illustrates an example gas turbine engine 20 thatincludes a fan section 22, a compressor section 24, a combustor section26 and a turbine section 28. Alternative engines might include anaugmenter section (not shown) among other systems or features. The fansection 22 drives air along a bypass flow path B while the compressorsection 24 draws air in along a core flow path C where air is compressedand communicated to a combustor section 26. In the combustor section 26,air is mixed with fuel and ignited to generate a high pressure exhaustgas stream that expands through the turbine section 28 where energy isextracted and utilized to drive the fan section 22 and the compressorsection 24.

Although the disclosed non-limiting embodiment depicts a turbofan gasturbine engine, it should be understood that the concepts describedherein are not limited to use with turbofans as the teachings may beapplied to other types of turbine engines; for example a turbine engineincluding a three-spool architecture in which three spoolsconcentrically rotate about a common axis and where a low spool enablesa low pressure turbine to drive a fan via a gearbox, an intermediatespool that enables an intermediate pressure turbine to drive a firstcompressor of the compressor section, and a high spool that enables ahigh pressure turbine to drive a high pressure compressor of thecompressor section.

The example engine 20 generally includes a low speed spool 30 and a highspeed spool 32 mounted for rotation about an engine central longitudinalaxis A relative to an engine static structure 36 via several bearingsystems 38. It should be understood that various bearing systems 38 atvarious locations may alternatively or additionally be provided.

The low speed spool 30 generally includes an inner shaft 40 thatconnects a fan 42 and a low pressure (or first) compressor section 44 toa low pressure (or first) turbine section 46. The inner shaft 40 drivesthe fan 42 through a speed change device, such as a geared architecture48, to drive the fan 42 at a lower speed than the low speed spool 30.The high-speed spool 32 includes an outer shaft 50 that interconnects ahigh pressure (or second) compressor section 52 and a high pressure (orsecond) turbine section 54. The inner shaft 40 and the outer shaft 50are concentric and rotate via the bearing systems 38 about the enginecentral longitudinal axis A.

A combustor 56 is arranged between the high pressure compressor 52 andthe high pressure turbine 54. In one example, the high pressure turbine54 includes at least two stages to provide a double stage high pressureturbine 54. In another example, the high pressure turbine 54 includesonly a single stage. As used herein, a “high pressure” compressor orturbine experiences a higher pressure than a corresponding “lowpressure” compressor or turbine.

The example low pressure turbine 46 has a pressure ratio that is greaterthan about 5. The pressure ratio of the example low pressure turbine 46is measured prior to an inlet of the low pressure turbine 46 as relatedto the pressure measured at the outlet of the low pressure turbine 46prior to an exhaust nozzle.

A mid-turbine frame 58 of the engine static structure 36 is arrangedgenerally between the high pressure turbine 54 and the low pressureturbine 46. The mid-turbine frame 58 further supports bearing systems 38in the turbine section 28 as well as setting airflow entering the lowpressure turbine 46.

Airflow through the core airflow path C is compressed by the lowpressure compressor 44 then by the high pressure compressor 52 mixedwith fuel and ignited in the combustor 56 to produce high speed exhaustgases that are then expanded through the high pressure turbine 54 andlow pressure turbine 46. The mid-turbine frame 58 includes vanes 60,which are in the core airflow path and function as an inlet guide vanefor the low pressure turbine 46. Utilizing the vane 60 of themid-turbine frame 58 as the inlet guide vane for low pressure turbine 46decreases the length of the low pressure turbine 46 without increasingthe axial length of the mid-turbine frame 58. Reducing or eliminatingthe number of vanes in the low pressure turbine 46 shortens the axiallength of the turbine section 28. Thus, the compactness of the gasturbine engine 20 is increased and a higher power density may beachieved.

The disclosed gas turbine engine 20 in one example is a high-bypassgeared aircraft engine. In a further example, the gas turbine engine 20includes a bypass ratio greater than about six (6), with an exampleembodiment being greater than about ten (10). The example gearedarchitecture 48 is an epicyclical gear train, such as a planetary gearsystem, star gear system or other known gear system, with a gearreduction ratio of greater than about 2.3.

In one disclosed embodiment, the gas turbine engine 20 includes a bypassratio greater than about ten (10:1) and the fan diameter issignificantly larger than an outer diameter of the low pressurecompressor 44. It should be understood, however, that the aboveparameters are only exemplary of one embodiment of a gas turbine engineincluding a geared architecture and that the present disclosure isapplicable to other gas turbine engines.

A significant amount of thrust is provided by airflow through the bypassflow path B due to the high bypass ratio. The fan section 22 of theengine 20 is designed for a particular flight condition—typically cruiseat about 0.8 Mach and about 35,000 feet. The flight condition of 0.8Mach and 35,000 ft., with the engine at its best fuel consumption—alsoknown as “bucket cruise Thrust Specific Fuel Consumption (‘TSFC’)”—isthe industry standard parameter of pound-mass (lbm) of fuel per hourbeing burned divided by pound-force (lbf) of thrust the engine producesat that minimum point.

“Low fan pressure ratio” is the pressure ratio across the fan bladealone, without a Fan Exit Guide Vane (“FEGV”) system. The low fanpressure ratio as disclosed herein according to one non-limitingembodiment is less than about 1.50. In another non-limiting embodimentthe low fan pressure ratio is less than about 1.45.

“Low corrected fan tip speed” is the actual fan tip speed in ft/secdivided by an industry standard temperature correction of [(Tram°R)/(518.7°R)]^(0.5). The “Low corrected fan tip speed”, as disclosedherein according to one non-limiting embodiment, is less than about 1150ft/second.

The example gas turbine engine includes the fan 42 that comprises in onenon-limiting embodiment less than about twenty-six (26) fan blades. Inanother non-limiting embodiment, the fan section 22 includes less thanabout twenty (20) fan blades. Moreover, in one disclosed embodiment thelow pressure turbine 46 includes no more than about six (6) turbinerotors schematically indicated at 34. In another non-limiting exampleembodiment the low pressure turbine 46 includes about three (3) turbinerotors. A ratio between the number of fan blades 42 and the number oflow pressure turbine rotors is between about 3.3 and about 8.6. Theexample low pressure turbine 46 provides the driving power to rotate thefan section 22 and therefore the relationship between the number ofturbine rotors 34 in the low pressure turbine 46 and the number ofblades 42 in the fan section 22 disclose an example gas turbine engine20 with increased power transfer efficiency.

Referring to FIG. 2 with continued reference to FIG. 1, the enginestatic structure 36 includes a front center body 62 that defines aportion of the core flow path C and also supports the gearedarchitecture 48. The front center body 62 further includes a gutterportion 64 that diverts lubricant exhausted from the geared architecture48 into an auxiliary lubricant supply 78 disposed within a first casestructure 76. The first case structure 76 is attached to a forwardflange 68 of the front center body 62.

The front center body 62 is an annular case structure and is a singleunitary structure formed as one part that includes structural featuressupporting the geared architecture 48 and a forward bearing assembly 90.The forward bearing assembly 90 supports rotation of the inner shaft 40.The front center body 62 extends radially outward from the forwardbearing assembly 90 to an outer surface to which portions of a corenacelle structure 92 may be attached.

A flex support 94 mounts to the front center body 62 for supporting thegeared architecture 48. The geared architecture 48 requires a constantsupply of lubricant to journal bearings 96 supporting rotation ofintermediate gears 98. Moreover, gear mesh interfaces between theintermediate gears 98, a ring gear 102 circumscribing the intermediategears 98 and a sun gear 100 driving the intermediate gears receivelubricant. Lubricant from the geared architecture 48 is exhaustedradially outward and into the gutter portion 64 that surrounds thegeared architecture 48. The example gutter portion 64 is an integralpart of the front center body 62 and mates to the first case structure76.

Referring to FIG. 3 with continued reference to FIG. 2, the gutterportion 64 includes a first channel 70 that accumulates lubricantexhausted radially outward from the geared architecture 48. Lubricant isdriven circumferentially by windage generated by the rotating parts ofthe geared architecture 48 to pump lubricant circumferentially into asecond channel 72 in communication with the auxiliary lubricant supply78 within the first case structure 76. A web portion 74 extends from thepassage portion 66 of the front center body 62 to support the gutterportion 64 proximate the geared architecture 48 and the first casestructure 76.

Referring to FIGS. 4 and 5 with continued reference to FIG. 2, thegutter portion 64 abuts the first case structure 76 without fastenersand communicates lubricant with the auxiliary lubricant supply 78.Because fasteners are not utilized to provide a flow path between thegutter portion 64 and the auxiliary lubricant supply 78, an extendedpassage 82 is provided at an outlet 80 for lubricant flow. The extendedpassage 82 protrudes forward into the first case structure 76 tosubstantially prevent lubricant leakage. The extended passage 82 issubstantially tubular in cross-section to define the outlet 80 into theauxiliary lubricant supply 78.

The first case structure 76 includes an aft extending passage 86 thatprotrudes into an exhaust passage 88 of the gutter portion 64. The aftextending passage 86 prevents leakage from lubricant overflow from theauxiliary lubricant supply 78. The aft extending passage is asubstantially tubular in cross-section to define the exhaust passage 88.Accordingly, passage of lubricant between the gutter portion 64 and thefirst case structure is facilitated without complex seals. Moreover, thegutter portion 64 abuts the first case structure 76 without requiringadditional fasteners.

Referring to FIG. 6 with continued reference to FIG. 2, the front centerbody 62 is a continuous unitary structure that includes the passageportion 66, the forward flange 68 and the gutter portion 64. The passageportion 66 includes circumferentially spaced apart struts (not shown)around which airflow through the core airflow path C flows. The passageportion 66 provides a substantially annular path for airflow through thecore airflow path C. The gutter portion 64 extends radially inward froman inner surface 104 of the passage portion 66. The gutter portion 64 isa continuous uninterrupted surface in cross-section of the front centerbody 62. The gutter portion 64 includes the first channel 70 forgathering lubricant exhausted from the geared architecture 48 and thesecond channel 72 for exhausting lubricant to the auxiliary lubricantsupply 78.

Although the disclosed example does not include seals between the gutterportion and the auxiliary lubricant supply, seals may be utilized toprevent lubricant leakage during extreme maneuvering conditions, such asduring negative or zero G maneuvers.

Accordingly, the disclosed front center body 62 includes the gutterportion 64 as an integral portion to eliminate seals and connectionsrequired when utilizing a separately installed gutter. Moreover, thefront center body 62 defines a single unitary structure that provides aportion of the passage 66 and also includes the gutter portion 64 tosimplify assembly and reduce complexity by eliminating an attachmentflange and accompanying fasteners.

Although an example embodiment has been disclosed, a worker of ordinaryskill in this art would recognize that certain modifications would comewithin the scope of this disclosure. For that reason, the followingclaims should be studied to determine the scope and content of thisdisclosure.

What is claimed is:
 1. A fan drive gear system for a turbofan enginecomprising: a gear assembly; and a front center body supporting the gearassembly, the front center body comprises an annular case structureformed as one part, the front center body including a passage portionfor defining a portion of a core flow path, a forward flange configuredfor attachment to a first case structure forward of the front centerbody and the gear assembly, a bearing support portion disposed aft ofthe gear assembly and a gutter portion disposed on a radially inner sideof the front center body, wherein the passage portion and the gutterportion are continuous uninterrupted surfaces of the front center body,wherein the gutter portion includes a peak comprising a radiallyoutermost point of the gutter portion about the entire annular surfaceaccumulating lubricant.
 2. The fan drive gear system as recited in claim1, wherein the first case structure includes an auxiliary lubricantsupply and the gutter portion includes an outlet extending axiallyforward into the first case structure for communicating capturedlubricant from the gear assembly to the auxiliary lubricant supply. 3.The fan drive gear system as recited in claim 2, wherein the gutterportion includes a first channel for gathering lubricant exhausted fromthe gear assembly and a second channel for exhausting lubricant from theauxiliary lubricant supply.
 4. The fan drive gear system as recited inclaim 3, wherein the passage portion, the forward flange and the gutterportion comprise a continuous uninterrupted cross-section of the frontcenter body.
 5. The fan drive gear system as recite in claim 1, whereinthe radially outermost point is disposed at a center of the gutterportion.
 6. The fan drive gear system as recited in claim 1, wherein thefront center body includes an integrally formed web portion extendinginward to support the gutter portion proximate the gear assembly.